Unless otherwise indicated herein, the materials described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
Craniomaxillofacial surgery is performed routinely in the United States and around the world for numerous problems involving the skull, including craniosynostosis (premature fusion of the cranial sutures), skull deformities associated with syndromes such as Crouzon Syndrome and Apert Syndrome; skull deformities resulting from the resection of both benign and malignant tumors, and complex craniofacial trauma involving the bones of the face and skull. These surgeries may involve the alteration or correction of the shape and structure of the skull, face and jaws and often require the repair, manipulation and fixation of bone.
Presently, the approximation and fixation of bone is typically accomplished with mechanical fastening systems, such as screws and plates. Tissue conditions, limited space, and access to the surgical site often present particular challenges to the practitioner. For example, in some cases, mechanical fixation is complicated or even prevented altogether due to a lack of tissue surface area or tissue substrate depth sufficient to afford an adequate secure location for the fixation device. In addition, standard mechanical attachment methods in the context of bone repairs involve a series of labor intensive and sometimes complicated tasks.
At present, several types of craniofacial surgery plating systems are currently commercially available. Both titanium and resorbable, polymer-based systems utilizing plates and screws are routinely utilized for the stabilization of bones during reconstruction in various craniomaxillofacial surgeries. These systems, however, often require cumbersome power equipment that necessitates additional operating room staff training and additional surgical time that increases the cost of the operating room, anesthesia time and surgical time. Sonic welding products, such as the Sonic Weld™ produced by KLS Martin, utilize a plate and resorbable tacks inserted into a hole drilled into the bone tissue and welded in place with an ultrasonic welding device. While these products do not use screws, holes must still be drilled into the bone tissue for placement of the tacks, which melt and disseminate into the trabecula of the bone with unknown consequences on growth and, development.
The type, weight and amount of material used in plating present additional challenges. Internal fixation devices, such as those used in craniomaxillofacial surgery historically have been made of various materials including metals such as titanium. Polylactic acid or polylactide polymers, such as poly(L-lactic acid) (PLLA) and poly(lactic-co-glycolide) (PLGA) have also been used in implantable devices. As compared to metallic devices, fixation devices made of these types of polymers do not corrode, can be constructed to avoid stress yielding, and are resorbable. Further, these devices may be particularly useful in the pediatric patient population as their resorption eliminates any adverse or restrictive effect that permanent plates would impose on craniomaxillofacial growth and development. Resorption of plates and screws fabricated from these polymers occurs approximately 2 years following placement. While use of biodegradable and absorbable materials is preferred by the surgical community, many of the existing mechanical systems are fabricated from metal and are non-resorbable. Conventional plating systems utilizing screws can often weaken the underlying bone or tissue, leading to decreased trabecular bone score. In some cases, failure of the screws can occur. Further, the thickness of these devices necessary to support screws, and the screws themselves, may be uncomfortable for the patient, be visible from the outer tissue surface, or interfere with healing.
Although some tools and materials have been developed to overcome the challenges and shortcomings described above, the fixation devices are still often bulky and cumbersome and time consuming to implant. A need still exists for a method and device that can eliminate the need for screws, but still provide satisfactory bony stabilization for craniofacial reconstruction and other reconstructive or orthopedic surgeries by (1) simplifying and expediting the intra-operative application of plates to the bone, and (2) removing the need for drilling holes in the bone tissue, thereby obviating the need for bulky power drilling equipment. Such a method and device would eliminate many of the surgical steps required to place mechanical fixation devices. In particular, drilling, tapping to produce threading, and placement of fixation pins or screws would no longer be necessary. Further, a device which utilizes a biocompatible, absorbable and lightweight polymer material may also address many of the above issues. It may also be useful to provide an internal fixation system that contributes to the quality of bone healing by the administration of growth factors or other biologically-active (bioactive) molecules.